Re: Forcing Argument Evaluation
- To: mathgroup at smc.vnet.net
- Subject: [mg49906] Re: [mg49848] Forcing Argument Evaluation
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Thu, 5 Aug 2004 09:22:28 -0400 (EDT)
- References: <200408041446.KAA20125@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
On 4 Aug 2004, at 16:46, Scott Guthery wrote:
>
> f[x_] := x^2;
> a = {f,f/2};
>
> a[[1]][2]
> 4
>
> a[[2]][[2]
> f/2[2]
>
> I know I'm missing something fundamental.
>
> Cheers, Scott
>
>
It's the same problem again, which I already once explained. The
algebra of functions is not implemented in Mathematica so although f is
a function f/2 is not a function. So you can't expect f/2[2] to have
return anything. If you really want implement the algebra of fucntions
you could do something like this:
Unprotect[Times,Plus];
(a_?NumericQ * f_)[x_]:=a f[x]
(f_+g_)[x_]:=f[x]+g[x]
(f_*g_)[x_]:=f[x]*g[x]
Protect[Times,Plus]
Now
f[x_]:=x^2;
a={f,f/2};
a[[2]][2]
2
Andrzej Kozlowski
Chiba, Japan
http://www.mimuw.edu.pl/~akoz/
- References:
- Forcing Argument Evaluation
- From: "Scott Guthery" <sguthery@mobile-mind.com>
- Forcing Argument Evaluation